In the diagnosis and treatment of breast cancer, it is often necessary to remove multiple tissue samples from a suspicious mass. The suspicious mass is typically discovered during a preliminary examination involving visual examination, palpitation, X-ray, MRI, ultrasound imaging or other detection means. When this preliminary examination reveals a suspicious mass, the mass must be evaluated by taking a biopsy in order to determine whether the mass is malignant or benign. Early diagnosis of breast cancer, as well as other forms of cancer, can prevent the spread of cancerous cells to other parts of the body and ultimately prevent fatal results.
A biopsy of the breast, for example, can be performed by either an open procedure or a percutaneous method. The open surgical biopsy procedure first requires localization of the lesion by insertion of a wire loop, while using a visualization technique, such as X-ray or ultrasound. Next, the patient is taken to a surgical room where a large incision is made in the breast, and the tissue surrounding the wire loop is removed. This procedure causes significant trauma to the breast tissue, often leaving disfiguring results and requiring considerable recovery time for the patient. This is often a deterrent to patients receiving the medical care they require. The open technique, as compared to the percutaneous method, presents increased risk of infection and bleeding at the sample site. Due to these disadvantages, percutaneous methods are often preferred.
Percutaneous biopsies have been performed using either fine needle aspiration or core biopsy in conjunction with real-time visualization techniques, such as ultrasound, mammography (X-ray), MRI, PET, CT, terahertz technologies, etc. Fine needle aspiration involves the removal of a small number of cells using an aspiration needle. A smear of the cells is then analyzed using cytology techniques. Although fine needle aspiration is less intrusive than an open procedure, only a small amount of cells are available for analysis. In addition, this method does not provide for a pathological assessment of the tissue, which can provide a more complete assessment of the stage of the cancer, if found. In contrast, in core biopsy a larger fragment of tissue can be removed without destroying the structure of the tissue. Consequently, core biopsy samples can be analyzed using a more comprehensive histology technique, which indicates the stage of the cancer. In the case of small lesions, the entire mass may be removed using the core biopsy method. For these reasons core biopsy is preferred, and there has been a trend towards the core biopsy method, so that a more detailed picture can be constructed by pathology of the disease's progress and type.
The first core biopsy devices were of the spring advanced, “Tru-Cut” style consisting of a hollow tube with a sharpened edge that was inserted into the breast to obtain a plug of tissue. This device presented several disadvantages. First, the device would sometimes fail to remove a sample, therefore, requiring additional insertions. This was generally due to tissue failing to prolapse into the sampling notch. Secondly, the device had to be inserted and withdrawn to obtain each sample, therefore, requiring several insertions in order to acquire sufficient tissue for pathology.
Vacuum assisted core biopsy devices were subsequently developed that required only a single insertion into the biopsy site to remove multiple tissue samples. An example of a vacuum assisted core biopsy device incorporates a tube within a tube design that includes an outer piercing needle having a sharpened end for piecing the tissue. The outer tube has an opening for receiving tissue. An inner tube is slidingly disposed within the outer tube, and serves to cut tissue that has prolapsed into the opening in the outer cannula. A vacuum is used to draw the tissue into the opening in the outer cannula.
Vacuum assisted core biopsy devices are available in handheld (for use with ultrasound) and stereotactic (for use with X-ray) versions. Stereotactic devices are mounted to a stereotactic unit that locates the lesion and positions the needle for insertion. In preparation for a biopsy using a stereotactic device, the patient lies face down on a table and the breast protrudes from an opening in the table. The breast is then compressed and immobilized by two mammography plates. The mammography plates create images that are communicated in real-time to the stereotactic unit. The stereotactic unit then signals the biopsy device and positions the device for insertion into the lesion by the operator.
In contrast, when using the handheld model, the breast is not immobilized. Rather the patient lies on her back and the doctor uses an ultrasound device to locate the lesion. The doctor must then simultaneously operate the handheld biopsy device and the ultrasound device.
While the vacuum assisted core biopsy device presented an advancement in the field of biopsy devices, several disadvantages remain with some of the currently marketed devices. For example, when using the current biopsy devices, physicians have encountered significant difficulties severing the tissue. For instance, the inner cutter often fails to completely sever the tissue. When the inner cutting needle is withdrawn, no tissue sample is present (dry tap), and therefore, reinsertion is required. In the case of the vacuum assisted core biopsy device described above, the failure to completely sever the tissue after the first advancement of the inner cutter results in a necessary second advancement of the inner cutter. In this event, the procedure is prolonged, which is significant because the amount of trauma to the tissue and, ultimately, to the patient is greatly affected by the length of the procedure. Therefore, it is in the patient's best interest to minimize the length of the procedure by making each and every attempt at cutting the tissue a successful and complete cut.
In light of the foregoing disadvantages, a need remains for a tissue removal device that reliably applies a vacuum without becoming plugged with blood and bodily fluids. A need also remains for a tissue removal device that is entirely disposable so that both exposure to bio-hazard and clean-up time are significantly minimized, while convenience is maximized. A further need remains for a tissue removal device that completely severs the maximum amount of tissue without requiring numerous attempts at cutting the tissue. A need also remains for a tissue removal device that is compatible with multiple imaging modalities. Finally, a need remains for a biopsy tissue removal device that is easy to use and does not cause a surgeon strain during use, but provides satisfactory access to a lesion to be biopsied.